This invention relates to a light- and thermosetting resin composition and a process for producing an insulated electrical machinery or appliance by using such resin composition. More particularly, it relates to a light- and thermosetting resin composition which is suited for insulation and secure fixing of the electrical machinery and appliances and which can provide the machinery and appliances with excellent compatibility with enameled copper wires, particularly those using as coating material such resins as polyester (polyester-coated wire, hereinafter referred to as PEW), polyesterimide (polyesterimide-coated wire, hereinafter referred to as EIW) or urethane (urethane-coated wire, hereinafter referred to as UEW), and is also capable of improving the reliability and performance of the electrical machinery and appliances and shortening the time required for the insulation treatment of such machinery and appliances. It is also envisaged in this invention to provide a process for producing electrical machinery and appliances by using such resin composition.
There has been seen lately a marked tendency toward smaller size and lighter weight, intensification of the use conditions and improvement of reliability of the electrical machinery and appliances, and such tendency has given rise to a request for the improvements of adhesive strength and crack, heat and chemical resistance of insulating varnish used for such machinery and appliances as well as shortening of the treating time with such insulating varnish from the standpoint of productivity. In order to meet such requirement, unsaturated polyester resins, which are excellent in said properties, have been used in place of the conventional solvent type varnish, and further unsaturated epoxy ester resins obtained by reacting polyepoxide with an .alpha.,.beta.-unsaturated monobasic acid, which are even more excellent than said unsaturated polyester resins in adhesive strength, crack and chemical resistance, etc., have been used as insulating varnish for rotary machinery and appliances such as stator, armature and the like.
A high operational reliability is required for the rotary machinery and appliances, and the insulating varnish applied thereof is required to have good compatibility with the enameled wires used in such machinery. The conventional unsaturated epoxy ester resins have usually a resin acid value of about 10 to 20, and among the insulating varnishes prepared by dissolving such unsaturated epoxy ester resins in an .alpha.,.beta.-unsaturated ethylenic monomer, there were those which would cause peel-off or swelling of the coating during heat-curing, particularly when their solvent resistance was poor or when using PEW, EIW or UEW with improper baking, resulting in unsatisfactory electrical insulation. Also, when a metallic soap such as cobalt naphthenate, cobalt octenoate, manganese naphthenate, lead naphthenate or the like is added as curing accelerator in such insulating varnish, there would be produced a precipitate as time passes. Further, a relatively long time is required for the insulating treatment of the rotary machinery and appliances with these insulating varnishes as such treatment usually necessitates heat-curing at 100.degree. to 150.degree. C. for 2 to 5 hours. Moreover, in the prior art, the cross-linking monomer would volatilize away in the course of heat-curing. Thus, a better insulation treating method has been required from the viewpoint of saving of material and prevention of pollution, too.